**3. Results**

112 New Approaches to the Study of Marine Mammals

are presented as ug/g wet weight.

*2.2.1. Chemical treatments* 

*2.2.2. Cytotoxicity assay* 

*2.2.3. Chromosome damage assay* 

reference materials, a duplicate sample and a pre-digestion spike. Instrument response was evaluated initially and after 10 samples, using commercially available calibration verification standards and a blank. All calibration verifications were within the acceptance criterion of 85-115% recovery and the preparation blank values were below 3x the limit of detection. Standard reference materials were used to assess method performance, where applicable. Interference check solutions were analyzed with all sample runs to check for matrix effects which might be interfering with sample analysis. The mean limit of detection (LOD) was the lowest analyte concentration likely to be reliably distinguished from the blank and at which detection is feasible. The LOD was previously determined by utilizing both the measured blank and test replicates of a matrix matched sample known to contain a low concentration of analyte. All samples were diluted 2x for analysis by ICP-MS. All data

**2.2. Determining if Cr is cytotoxic and genotoxic to cultured whale cells** 

Cr, the original exposure to Cr would almost certainly have been to Cr(VI).

of molarity would overestimate the dose. Thus, its units are weight per surface area.

There are two major biologically relevant valence states for chromium, hexavalent and trivalent, with the hexavalent forms considered more potent than the soluble forms. This study focused on the hexavalent form because the marine environment favors the hexavalent form [5]. Moreover, the total Cr levels in the whales were found to be high and considering that Cr(III) is poorly absorbed by mammals [6], for the whales to accumulate these levels of total

We treated whale cells with both a water soluble (sodium chromate) and a water-insoluble particulate (lead chromate) to determine its ability to induce DNA damage. The concentration units for the two chemicals are different (uM for sodium chromate and ug/cm2 for lead chromate) because sodium chromate dissolves fully in water and thus is a solution, while lead chromate does not and instead forms a slurry of particles in water. The cells were treated with this slurry of intact particles. Since all the lead chromate is not dissolved to express it in units

Cells were seeded into a 6 well plate and allowed to grow for 48 h. The cells were treated for 24 h with 1-25 uM of sodium chromate or 0.05-10 ug/cm2 lead chromate. After 24 h we harvested the cells using a standard protocol [7]. Briefly, cells were harvested, counted and re-plated into 100 mm dishes at colony forming density, allowed to grow approximately 2 weeks, then stained and counted. Treated dishes were compared to the untreated control.

Cells were seeded into 100 mm dishes and allowed to grow for 48 h and treated as they were in the cytotoxicity assay described above. Cells were harvested and analyzed using published protocols [7]. Briefly, cells were harvested, treated with potassium chloride to
